Two separate projects are proposed. Project 1 ("Epidemiology of Depression in the Elderly") is a longitudinal prospective study of a representative sample of 900 elderly persons. Subjects are assessed on a wide range of measures at point of entry into the study. They will be followed for two years during which time their depression level will be monitored on a monthly basis. Clinical assessments will be done on subjects who become depressed. Four types of hypotheses will be tested: 1) What are the distinguishing characteristics of elderly persons who become depressed? 2) What are the distinguishing characteristics of elderly persons who are depressed? 3) What are the distinguishing characteristics of elderly persons who are depressed and who recover? 4) What are the distinguishing characteristics of elderly persons who have a history of having been depressed earlier in life? Project 2 has three objectives: 1) To adapt an existing conceptualization of the key ability factors underlying cognitive performance to the study of the aging. 2) To use the measurement devices constructed as per objective 1 to evaluate the effects of cardiovascular conditioning on the cognitive behavior of elderly depressed and elderly non-depressed Ss. 3) The measurement devices will be used to assess cognitive functioning as a function of age.